The present invention relates to a push switch employing a click spring, and more particularly, to a push switch employing a click spring designed to stabilize contact between a traveling contact and a fixed contact.
Conventionally, a push switch employing a spherical click spring is used for control signal input for a variety of audio, video and other electronic equipment.
FIGS. 4 and 5 show one example of a conventional push switch employing a conventional spherical click spring. As shown in the diagrams, in the conventional push switch 1, a fixed contact 4 and a fixed contact 5 are provided at a center and an exterior edge of an interior floor of a button holder 3 of a resin base 2. Further, a spherical click spring 6 is inserted inside the button holder 3, an outer edge part of the spherical click spring 6 is bonded to the outer fixed contact 5, and a central part is provided so as to be positioned atop the fixed contact 4. Additionally, a small-diameter top part 7a of a push button 7 placed on a top of the spherical click spring 6 projects upward from a central hole in a button cover 8 that is affixed to a top of the base 2.
In the above-described push switch 1, when the push button 7 is pressed downward, as shown in FIG. 5 a convex part 7b provided on a central part of a bottom surface of the push button 7 depresses the spherical click spring 6 that functions as a traveling contact, inverting it so that the center of the spherical click spring 6 contacts the central fixed contact 4. As a result, the spherical click spring 6 establishes an electrical conduction between the fixed contact 4 and outer fixed contact 5.
In the above-described push switch 1, when the spherical click spring 6 inverts, a center point C of the spherical click spring 6 contacts the central fixed contact 4 as shown in FIG. 5 and FIG. 6 and a state of electrical conduction is obtained between the fixed contact 5 and the fixed contact 4. However, if particles and the like remaining inside the push switch 1 adhere to the top of the central fixed contact 4, then an adequate electrical conduction is not obtained and problems arise with respect to the electrical properties of the apparatus such as the electric capacity, resistance and so forth, interfering with the reliability of the apparatus as a push switch.
The present invention was conceived as a solution to the above-mentioned problem, and has as its object to provide a push switch utilizing an improved click spring that avoids the adverse effects of particulate matter and stabilizes the electrical conduction between fixed contacts during operation of the switch.
The present invention was proposed in order to achieve the above-described objects, and comprises a push switch comprising a fixed contact and a spherical click spring that functions as a traveling contact, the click spring comprising a projection that projects upward from a central part of the click spring and an aperture part open at a bottom being formed inside the projection, such that when the projection is depressed a bottom edge of the aperture part and the fixed contact form a line contact.
A projection that projects upward in order to form an aperture portion open at the bottom is provided on a center portion of the spherical click spring used in the push switch of the present invention, so when the push button is pressed the spherical click spring is depressed and inverted, contacting the center portion of the spherical click spring with the central fixed contact and causing an electrical conduction to form between the central fixed contact and the outer fixed contact. At this time, the bottom edge of the aperture part open at the bottom forms a line contact with the central fixed contact in a circular or other, square shape, so the pressure with which the spherical click spring contacts the central fixed contact increases, cutting out dust particles adhering to the top of the central fixed contact and enabling adverse effects of dust particles and the like on the electrical conduction between fixed contacts to be reduced to a minimum and improving the stability of the electrical conduction of the push switch.